RMRecker, created by AnomyWare, is specifically designed for “editing resources, such as splash screens, icons, and glyphs, in your RPG Maker games quick and easy”.

RM Recker

With it, you can change any of the three logos, the glyphs and icons used in the game with your own, then save them. The way that RMRecker does this is it patches the EXEcutable RPG_RT file, overwriting the "defaults". It certainly is a quick and easy process and, although it was created with RM2K/3 in mind, it can be used with other EXE files as well.

There are some limitations:

You can only use 8-bit images. It won’t accept 24-bit high color images unless you decrease the color depth first.

While glyphs can be BMP, PNG or the proprietary XYZ formats, logos can only be PNG or XYZ formats.

The current version is v1.0 Beta 2, but there have been no apparent updates since 2003; it is still a useful utility nevertheless.